This Calendar 11 icon is a responsive icon. This means that it's optimized for four resolutions, from tiny 16x16 until highly detailed 80x80. The style comes from the latest Microsoft Office, which makes it perfect for any Windows applications, in particular, those with ribbon toolbar control. Unlike other icon packs that have merely hundreds of icons, this monster icon pack contains 15,700 icons, all in the same style and quality.
It is the number 11 contained within a rectangle. It appears to be a page from a calendar that is bound at the top. There are two binding rings represented by two small rectangles on the top. The date, which is 11, is written on the page below the binding.